Sterling Power BB1260 Battery to Battery (B2B) Charger – Review

The Sterling Power BB1260 Battery to Battery (B2B) Charger play a major role in keeping our camper van electrical system balanced and healthy. How’s that? The B2B charger uses the van alternator power to charge our house (auxiliary) battery while we drive. It’s an install-and-forget device: it turns itself ON/OFF automatically when driving the van, doing its things without user intervention. Neat! It means that we don’t have to worry about running out of power AND that the house battery lifespan is maximized. Sounds too good? Keep reading this review as we get into more details…

Vanlife Essentials!

How does it work?

The Sterling Power Battery to Battery charger is installed “between” the van battery and the house battery (more installation details further in this article). There is no switch or button to initiate the charge! You see, when you start your vehicle the alternator kicks-in and raise the voltage of the van battery in order to charge it. The B2B senses the higher voltage and turns itself ON automatically. Now when you turn your vehicle OFF, the alternator stops and the voltage of the van battery drops; the B2B senses the dropped voltage and turns itself OFF. All of that happens without user intervention (well, except the part where you drive your vehicle!).

Why is it beneficial to the house battery lifespan?

Each type of battery (Gel, AGM, Lithium, etc.) has a specific charge voltage; with an isolator or an ACR (instead of a B2B), the house battery receive a “random” voltage (same as the van battery). You probably heard of battery’s memory effect, right? It’s real! If a battery doesn’t get a proper multi-stage charge (bulk, absorption, float), it looses its total capacity and that’s non-reversible (knowledge is power: we recommend reading the Charging Profile section of our Electrical System page to really understand what that means). Bad charge = wasted money (the battery has to be replaced more often), so we think the B2B charger pretty much pays for itself in the long run.

Are solar power AND alternator power (B2B) both needed?

Here’s what we think about that:

If you live full time in your van, we say a B2B charger is a must. Energy is a basic need, it’s not cool worrying about running out of it…

If you take your van for adventures in summer only, you can probably live without it as solar can provide the bulk + absorption charge on its own.

For fall and spring adventures, we highly recommend it as the solar days get shorter and weaker. Alternator power is a good way to quickly go through the bulk charge, then solar power can complete the absorption stage.

For winter there’s no question about it, our opinion is that you want it. Sun angle is too low, solar day is too short and overcast weather is more common (for USA and Canada at least).

What we Like…

Surprisingly easy to install (scroll down for installation write-up)

Install-and-Forget!

Fast Charge (up to 60A during the bulk charge)

Provides a nice multi-stage charge that keeps the battery (Gel, AGM, Lithium, etc.) healthy in the long run

What we Don’t Like …

The internal cooling fan is quite noisy; think of a tiny hair dryer. If possible, install the Sterling charger further back away from driver / passenger seats to minimize the noise.

Models & Where to Buy

There are a few variants of the Sterling Power Battery to Battery charger, so make sure to select the appropriate one according to:

Input voltage (most likely 12V…)

Output voltage (most likely 12V…)

Charge current (30A or 60A).

It basically comes down to either BB1230 (12V input, 12V output, 30A) or BB1260 (12V input, 12V output, 60A) model. We highly recommend the BB1260 for a faster charge (so a short drive goes a long way 🙂 ), unless of course 60A is over the maximum current recommended for your battery.

Batteries generally have recommended and maximum charge current. Going overboard is a waste of space (this charger is bigger) and money.

Check your battery manual or data sheet to find out.

Make sure your alternator can handle that much current so that you’re not draining your van battery.

For example there are two alternator options on the Ford Transit: basic (150A) and Heavy-Duty (230A). It is believed (not official info) the Transit needs roughly 70A for itself (lights, radio, etc.), so we’re left with 80A extra current with the basic alternator and 160A extra current with the Heavy-Duty alternator. If you have the basic 150A alternator (80A extra current) and you’re charging your house battery at 120A, it probably means your are “borrowing” that extra power from the van battery…

Installing the Sterling BB1260 B2B Charger

Location

Make sure to install the B2B charger into a well vented space and do not obstruct the hot air exhaust:

Wiring and Electrical

It’s honestly quite simple. Here are the required connections:

Positive Input (From vehicle battery)

Positive Output (To house battery)

Negative (Common to vehicle and house battery)

Temperature sensor (To house battery negative post. Optional, but recommended. This is to correct the voltage according to temperature change)

For safety sake, remember to add fuses (or breakers) on the positive wires and to select the right wire diameter according to length / fuses. Not sure why or how? In this case, make sure to read our electrical system guide! We first start with the theory (so you understand what’s going on), then YOU do the work using our Interactive Diagram and our Tutorial:

Default Options

(Mode 2 is identical to mode 1, except it needs a live signal on the ignition feed input in order to charge)

ACTIVATION VOLTAGE: vehicle battery above 13.2v (for 5 seconds)

TURN-OFF VOLTAGE: vehicle battery below 13.2V

TURN-OFF TIMER: 240 seconds

(A timer is required to complement the regenerative braking aspect of modern Euro 5 / 6 + engines – where the alternator’s voltage can drop below 13V for a short period of time)

Because our Ford Transit 2016 does not have regenerative braking, we changed the turn-off timer to 30 seconds (procedure in manual). This is the prevent draining the van battery, especially when running errands (multiple short drives).

First Time Use

The unit will enter “config” mode at first startup; this is your opportunity to change the charging profile according to your battery type.

To find out which charging profile to select, check your battery manual.

First Time Use Configuration Sequence:

To initiate the first startup, turn on the vehicle and wait a few seconds. To indicate the B2B has turned ON, LEDs will light up, a beep will sound and the fan will run for 5 seconds. If none of that happens, try to “force-start” the unit: simply press and hold SETUP/ENTER for 5-9 seconds.

At this point, a LED is flashing to indicate the battery type (default = lead acid).

To change the battery type, press and hold SETUP/ENTER buttons for 10-12 seconds (up to 20 seconds); all LEDs are now flashing.

Scroll down (SELECT button) or up (ENTER button) to select your battery type; Press and hold SETUP/ENTER buttons for 2-3 seconds to confirm the selection.

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Thanks for all the info and wiring diagram. I am reading that the recommended charging rate for AGM batteries is 20% of the capacity (0.2C). I have a 200 AH AGM battery and would like to get the 1260 with 60A of charging but that is 0.3C. Did you have any issues charging your 220 AH AGM with the 60A Sterling? Should I get the 1230 or 1260? THANKS.

– An isolator put your house battery in parallel with your van battery. As a result, the house battery receive a “random” charge profile and might not get up to 100% in some case. Also, the alternator might overwork.
– A B2B charges the house battery with a proper profile (bulk/absorption/float, just like a smart charger would) and also act as current reducer so the alternator doesn’t overwork.

A battery charged with a B2B will last longer (especially flooded/gel/agm).

Question: I have been to a major battery supplier and asked about Lithiom Batteries. FYI… they sell millions of dollars of batteries yearly. I was told they were not safe. They supply batteries to major custom boat builders and said they cause alot of fires. Please advise.

In 2015 when we designed our van, we went with AGM (not lithium) because of safety concerns. Fast forward now to 2019, Lithium batteries now come with built-in BMS (Battery Management System): the BMS will disconnect the battery if any parameter is out of range (charge/discharge current, temperature, short circuit, etc). Technology has come a long way and many MANY people use Lithium them in their van/RV now. My advise would be to go for a major brand (Battle Born, Trojan, Relion, Renogy) and not worry about it. I think in 2019 Lithium is the way to go (until your battery is install outside your van and you’re dealing with freezing temperatures).

About to install the B2B charger (60amp) and I had a question about charging. When I normally charge from a plug-in 120v charger I shut down all the loads on the battery so it can charge correctly in three stages. When I do this I have the input go to an extension with two outputs, one for the charger and the other to plug my fridge in while charging so no load is on the battery during charging.

I am wondering if turning off loads while charging is needed with the Sterling charger? And if so, how do you approach?
Id like to be able to charge while driving and keep the fridge on but do not want to damage the batteries while charging them. Please let me know if you have solved for this or have any suggestions, thanks!

Great post! We have the Sterling BB1260 and BattleBorn Lithium 100aH battery installed. Our problem is that Sterling unit seems to only charge at the Float level (13.4) and never at the Bulk (14.4v) or Conditioning voltage (13.4) levels. We have reset our BB1260 to factory settings with the 30 second reset procedure and re-configured a custom charging profile of: Bulk 14.4v, Conditioning 13.4v, and Float 13.4v per BattleBorn specs. How do you initiate Bulk charging? Does the battery need to be close to empty? At what SOC % should I see (or hear) Bulk charging kick in?

The voltage is variable during the Bulk/boost stage and increases as the battery gets closer to the full charge (voltage starts low and get closer to abs voltage). I think you should set the B2B as follows:
– Bulk/abs: 14.4V
– Cond: 13.6V
– Float: 13.6V

So if my battery is at 30% SOC, it may start charging at the Float level initially, then only jump to the Bulk/Boost charging level closer to 100% SOC? When the battery is fully charge does the BB1260 idle at the Float level or possibly turns itself off?

I consider your post much better for the lay person to understand the operation of the BB1260 than the Sterling Owner’s Manual (too much information for the layperson).

It was my understanding that BB1260 when boost charging (in our case, set to 14.4v boost) the unit cranks up and starts its fan to generate the higher voltage 14.4v boost charge.

But we never hear this higher level of charging or see a voltage test output of 14.4v. The unit always outputs the same float voltage around 13.6v. We have contacted Sterling as well about this issue. Wondering if our unit is configured incorrectly or possibly needs service.

I’m installing the BB1260 into our van, and after reading the instructions and your electrical guide, I’m a bit unclear on something. I understand it’s a good idea to have a common ground between the house battery and starter battery, so I’m planning on connecting the negative bus bar to the negative ground in the van. I took a look at the BEMM (https://fordbbas.com/publications) Page 150 on the 2017 version shows all the grounding points. I assume I should use one of these grounding points instead of going all the way to the negative terminal of the starter battery. Are they all equal, and does the chasis actually carry the current, because the wires at the rear mount points I’m looking at are quite small (29-31)? Where did you connect the negative bus bar to?

I think I’m going to attach the negative bus bar to the rear mount points (BEMM 29), since it’s closer to the Sterling and I won’t have to run the negative wire all the way to the front. The wire currently going to BEMM 29 is quite small, but I now realize that the van chassis is actually the common ground, so the current won’t be flowing through the small wire anyways.

As another engineer, I spent a bunch of time researching B2B for my LiFe Sprinter. I found Kisae to make a much, much better solution that feels like it’s from the early 2000’s rather than the 80’s. Similar B2B charge spec plus MPPT solar charging in one small, quiet-ish, super easy to program, and inexpensive device. I’ve been running it between the Sprinter Alt + 200w panel and 170Ah Renogy LiFe since Sept ’18 with zero issues. Check it!

> You probably heard of battery’s memory effect, right? It’s real! If a battery doesn’t get a proper multi-stage charge (bulk, absorption, float), it looses its total capacity and that’s non-reversible

Capacity loss in lead-acid chemistries is due to hard sulphation, not memory effect.

For example there are two alternator options on the Ford Transit: basic (150A) and Heavy-Duty (230A). It is believed (not official info) the Transit needs roughly 70A for itself (lights, radio, etc.), so we’re left with 80A extra current with the basic alternator and 160A extra current with the Heavy-Duty alternator.

I caution against over-reliance on the Sterling. There’s a general perception in the off-grid van world that the Sterling is all that is needed to be protective of the alternator, but there’s also evidence suggesting that it is only protective in SOME ways, not in all ways.

My husband and I upgraded our Sprinter-based off-grid van to a 200 A Bosch alternator and installed a Sterling between it and our house battery. Within 17 months, the alternator clutch pulley failed on what should have been a viable set-up. I researched it, and found plenty of other stories on the internet about these alternators failing under high-demand scenarios when they are not supposed to.

The safest way to incorporate alternator charging is with a second engine alternator. If you use only one alternator, I would advise a real-time voltage monitoring and alarm system for your chassis battery because if the alternator begins to fail, that’s where it will be reflected first. You don’t want to find yourself stopped dead in the middle of an interstate highway, and that’s what will happen if you don’t catch the failure in time. That’s what ALMOST happened to me in the middle of rural Mississippi this past August. Fortunately I had an OBD and noticed my chassis battery dying in real time, such that I was able to intervene.

Sorry to hear that…
On our Transit, we went with the Heavy-Duty alternator option (230A) and hopefully it’s up to the task! I’m still lurking on the Transit forum and haven’t heard of people having issue with the Transit alternator.

Great article on a great solution! At the time I installed our BB1260 back in March of 2017 the LiFePO4 setting had no setting to shut down the charger when fully charged. I was forced to allow a floating charge. LiFePO4 batteries are not supposed to be float charged. I set the float charge voltage to the ambient voltage of my battery bank (around 3.2V per cell, as I recall) hoping that the current would be negligable. If Sterling still forces a float charge, how are you dealing with the float issue?

Antoine,
Another great review.
We switched to a Sterling-Power BB1230 (30 amp model) after switching to Battle Born lithums 6-7 months ago. So far performs a champ!
We did not go the ‘automatic’ route though. Since going lithium I’m more ‘hands on’ and keep an eye to the smartphone app and the Victron battery monitor and decided when to flip a switch turning on either solar charging or B2B charging via the Sterling model.
Since switching to lithium our reserve capacity is so much more than we had with lead-acid that we can go extended periods of time before needing any Sun or having to B2B or find a pedestal (we hate pedestals!).
So far we’ve not noticed the fan noise, but the 30 amp model might be quieter?//embedr.flickr.com/assets/client-code.js

Make sure that you don’t accidentally put it in standby during setup. We did and didn’t diligently check it until our big month long trip because the battery was always full. Then after days and days of rain our battery voltage level crashed in the middle of the night which caused our propane detector to turn on and off beeping to wake us up. (I assume this was because the current draw of the detector would lower the voltage and then turn off the detector, then with the detector off the voltage came up to turn the detector back on). Anyways it was a rude awakening on one of our Walmart nights. After trouble shooting a bit I realized that during the setup steps I did too many button pushes and put the unit in standby. As a result we were never getting a charge from the alternator.
Beside that I like the Sterling paired up with our Battle Born Lifpo4 battery.